Abstract: Abstract  Hand preference has been investigated in New World primates but the data obtained thus far are controversial. In this study we investigated hand preference in common marmosets,Callithrix jacchus, during the execution of a reaching for food task. We used 46 adult common marmoset males (n=27) and females (n=19) from the Universidade of Rio Grande do Norte colony, both wild and captive-born. To test the hand preference we used a device measuring 10 cm2, with a central hole 1 cm in diameter, to force the animal to use only one hand to reach for food on a food dish located underneath. Each animal was tested 5 times and had to make a maximum of 20 successful attempts per session. A total of 100 successful attempts per animal and 4,600 successful attempts for all animals were recorded during the experiment. Latency and duration of the sessions were measured and we found preference for the use of one of the hands in common marmoset individuals, i.e. 45 of total of 46 animals used significantly more the right or the left hand when performing the task. However no bias at the population level was found. Females born in captivity presented an increase in the duration of latency for the first successful attempt and in the total duration of the test sessions. These findings might be indicating differences associated with a natural tendency for females to be more selective and to spend more time exploring alimentary sources. Additionally, captive-born females may have a constrain in developing cognitive abilities regarding foraging since they have food available during most part of the time.

Abstract: Matrilineal kin-relations among wild bonobos (Pan paniscus) were studied by DNA analysis. Subject individuals were the members of E1 group, living at Wamba, Zaire, which has been studied since 1974. DNA samples were extracted from wadges that bonobos spat out when feeding on sugar cane. The D-loop region of mitochondrial DNA was amplified by the PCR method, and a nucleotide sequence of 350 base pairs was determined for 17 individuals. Nucleotide variations were found at 44 positions of the sequence. Based on these variations, 13 matrilineal units were divided into seven groups, and the mother of an orphan male was determined among several females. These genetic analyses, together with behavioral observation to date, revealed the following facts. High sequence variation in the target region indicated that females transfer between groups of bonobos, which is in agreement with supposition from long-term field studies. For females, there was no relationship between genetic closeness and social closeness that is represented by frequencies of proximity or grooming. After immigration into a new group, females form social associations with senior females without regard to kin relationship.

Abstract: Observations of play behavior were made on a troop of Japanese monkeys for five months. The troop consisted of 125 animals during the study period. Only 104 animals were observed playing with the troop members while the other 21 animals were never observed playing with other individuals. Two-member play was the most frequent. On the average, a monkey played with 20.7 individuals. A total of 6,068 play bouts were observed. The frequency of play appeared to be affected by age, sex, and degree of relatedness. One-year-old infant males played most with other members and the frequency of play decreased with age. Between monkeys whose disparity of age was less than two years, 5,763 bouts (95.0% of the total) were observed. Moreover, among sameaged monkeys who comprised 10.6% of the possible pair combinations, 2,739 play bouts (45.1%) were observed. Juvenile males played with same-sexed peers more than with opposite-sexed peers, whereas older juvenile females appeared to play with infants of both sexes. Individuals who were related and similarly-ranked tended to play together. There was no apparent preference for animals to play with the offspring of the highest-ranking female. Dominance rank of infnats and juveniles was primarily affected by rank of their mothers and to a lesser extent by play partners. Dominance rank of older juvenile males is more likely to be affected by play partners than females. It may be a critical time for males when they leave their natal troop and join a new troop. The timing of troop shifting by males seemed to be affected by the presence or absence of play-mates. For male Japanese monkeys, play is very important in developing social bonds. Play may act to perpetuate social bonds, enhance the chance of survival, and may contribute to their future reproductive success.

Abstract: Since the non-invasive field endocrinology techniques were developed, several fecal preservation and extraction methods have been established for a variety of species. However, direct adaptation of methods from previous studies for use in crested macaques should be taken with caution. We conducted an experiment to assess the accuracy and stability of fecal estrogen metabolite (E1C) and glucocorticoid metabolite (GCM) concentrations in response to several preservation parameters: (1) time lag between sample collection and fecal preservation; (2) long-term storage of fecal samples in 80% methanol (MeOH) at ambient temperature; (3) different degrees of feces drying temperature using a conventional oven; and (4) different fecal preservation techniques (i.e., freeze-drying, oven-drying, and field-friendly extraction method) and extraction solvents (methanol, ethanol, and commercial alcohol). The study used fecal samples collected from crested macaques (Macaca nigra) living in the Tangkoko Reserve, North Sulawesi, Indonesia. Samples were assayed using validated E1C and GCM enzyme immunoassays. Concentrations of E1C and GCM in unprocessed feces stored at ambient temperature remained stable for up to 8 h of storage after which concentrations of both E1C and GCM changed significantly compared to controls extracted at time 0. Long-term storage in 80% MeOH at ambient temperature affected hormone concentrations significantly with concentrations of both E1C and GCM increasing after 6 and 4 months of storage, respectively. Drying fecal samples using a conventional oven at 50, 70, and 90 °C did not affect the E1C concentrations, but led to a significant decline for GCM concentrations in samples dried at 90 °C. Different fecal preservation techniques and extraction solvents provided similar results for both E1C and GCM concentrations. Our results confirm previous studies that prior to application of fecal hormone analysis in a new species, several preservation parameters should be evaluated for their effects on hormone metabolite stability. The results also provide several options for fecal preservation, extraction, and storage methods that can be selected depending on the condition of the field site and laboratory.